Forming apparatus and method and object thus made

ABSTRACT

A method for making objects by forming a thermoformable sheet material includes forming the objects by interaction of a die assembly and a forming assembly. The method further includes, compressing and crushing a first portion of the sheet material by a crushing punch device before forming the objects and maintaining the first portion crushed during the forming operation to reduce the thickness thereof and to orientate chains of molecules that compose a structure of the sheet material at the first portion, in order to weaken the structure and the first portion. The first portion is thus easily perforable, tearable and breakable.

The invention relates to forming apparatuses and methods, in particularit relates to an apparatus and a method for making objects bycompression forming of a thermoformable sheet material. The inventionfurther relates to an object, in particular a cover for a container,obtained by said apparatus and method.

A known forming apparatus, associable with a thermoforming machine,typically comprises a mould consisting of a die and a punch. The die isprovided with a least one cavity configured for receiving, in a formingstep, the sheet material and is shaped with the external shape of theobject to be made.

The punch is in turn shaped in such a manner as to compress the sheetinside the cavity and, in cooperation with the cavity, to make theobject. In particular, in the forming step, the punch is movable towardsthe die and engages with the cavity so as to deform the sheet material.The latter is previously heated to a softening temperature that permitsthe plastic deformation thereof, increasing the plasticity anddeformability thereof.

The die is provided with conduits within which a fluid flows that isarranged for cooling the sheet material once it is deformed inside thecavity so as to bestow suitable mechanical features on the object made.

The forming apparatus can comprise a containing element, so-called bell,which encloses the punch and bounds a closed work zone. More precisely,the bell abuts and compresses the sheet material against the die,defining the work zone that is substantially isolated from the externalenvironment and into which compressed and heated air can be introducedthat assists the punch to make the sheet material adhere better to thewalls of the cavity.

The forming apparatus is typically associated with a forming machinecomprising a plurality of operating stations through which thethermoformable sheet material unwound from a reel is advanced bysuitable advancement means.

The operating stations comprise, for example, upstream and downstream ofthe forming station provided with the forming apparatus, respectively apreheating station, in which the sheet material is heated to a presetsoftening temperature, and a cooling station, in which the formed objectis cooled and thermally stabilised to ensure suitable resistance tomechanical stress.

The objects made with the known thermoforming apparatuses disclosedabove are easier to make and cheaper than objects obtained by extrusionor injection moulding processes.

The thickness of the sheet material is chosen in such a manner as toensure suitable features of resistance and toughness for the objectmade. Nevertheless, owing to the thicknesses generally used and themechanical features of the sheet material once it has been thermoformedand cooled, some operations on the aforesaid material are difficult toperform. In particular, it is generally difficult to make perforationsor incisions, unless sheets of material with a very reduced thicknessare used, which thickness is insufficient for making stiff, resistantand tough objects.

In the field of capsules or containers for preparing beverages inautomatic beverage machines, the need is known to be able to perforateeasily a capsule containing a (percolable, soluble, infusion) product toenable pressurised liquid, typically water, to be mixed with the productand the obtained beverage to exit. In particular, the capsules have tobe perforable by suitable means of the beverage machine and/or bycooperation between the capsule and such suitable means.

The capsules typically comprise a container in the shape of a cup closedabove by a cover.

The capsules and the covers made by a thermoforming process are not,however, generally perforable, as the thicknesses of the sheet materialthat would permit boring thereof would be insufficient to ensure thestability and the resistance of the capsule during injecting of thepressurised fluid at high temperatures.

For this purpose, capsules are used that are closed by a sheet ofaluminium or plastic film that are easily perforable and/or are providedwith a hole on the bottom wall (the bottom being made duringthermoforming), which hole is also closed by a film of aluminium or ofplastics.

Alternatively, capsules and covers have to be used that are produced byinjection moulding processes that enable portions of the object to bemade that have a reduced thickness and mechanical features that are suchas to enable a perforation or incision to be made on such objects.Nevertheless, such objects are particularly costly because of theprocess and the plastics to be used for the injection moulding.

One object of the present invention is to improve known methods andapparatuses to make objects forming a thermoformable sheet material.

Another object is to make a method and an apparatus that enable objectsto be formed that have high mechanical resistance and robustnessfeatures and is at the same time provided with easily perforableweakened portions.

A still other object is to make a method and an apparatus that enableobjects to be formed that are provided with weakened portions havingprecise and accurate thickness values.

A still further object is to obtain a forming apparatus that isconstructionally simple.

Still another object is to obtain a forming method and an apparatus thatenable the production costs of the objects to be lowered.

In a first aspect of the invention a method is provided for makingobjects according to claim 1.

In a second aspect of the invention an object is provided according toclaim 8.

In a third aspect of the invention an apparatus is provided according toclaim 9.

In a fourth aspect of the invention an apparatus is provided accordingto claim 10.

In a fifth aspect of the invention an apparatus is provided according toclaim 22.

In a sixth aspect of the invention a forming machine is providedaccording to claim 37.

The invention can be better understood and implemented with reference tothe attached drawings that illustrate some embodiments thereof by way ofnon-limiting examples, in which:

FIG. 1 is a schematic cross section of a forming apparatus according tothe invention in a first operating configuration;

FIG. 2 is a schematic cross section of the apparatus in FIG. 1 in asecond operating configuration;

FIG. 3 is a schematic cross section of the apparatus in FIG. 1 in athird operating configuration;

FIG. 4 is a partial enlarged view of a detail of the apparatus in FIG.3;

FIG. 5 is a plan view of an object, in particular a cover, made with theforming apparatus in FIG. 1;

FIG. 6 is a cross section according to the line VI-VI in FIG. 5;

FIG. 7 is a cross section of the cover in FIG. 5 associated with acontainer that is also makable with a version of the forming apparatusof the invention;

FIG. 8 is a partial and enlarged view of the object in FIG. 5 thatillustrates a perforation made on a portion thereof with a tip ofconical shape.

FIG. 9 is an histogram that shows a frequency distribution of a materialthickness obtainable by the method and the apparatus of the invention.

FIG. 10 is a schematic cross section of a variant of the formingapparatus according to the invention in a third operating configuration.

With reference to FIGS. 1 to 3 a forming apparatus 1 is shown forcompression-forming an object 50, shown in FIG. 4, from a thermoformablesheet material 40.

The object 50 comprises, for example, a cover that is usable for closinga container, as illustrated in FIG. 7.

The apparatus 1 can be associated with a forming machine, which is notshown, comprising a plurality of work stations, including a formingstation with which the apparatus 1 and other stations preceding andfollowing the forming station are associated. For example, upstream ofthe forming station a heating station of the sheet material 40 can beprovided to bring the sheet material 40 to high temperatures that aresuch as to enable the sheet material 40 to be softened and plasticallydeformed in the subsequent forming station. The sheet material 40 isheated to a temperature comprised between 100° C. and 180° C., inparticular between 140° C. and 165° C.

The apparatus 1 of the invention comprises die means 2 provided withcavity means 4 and forming means 3 cooperating with the cavity means 4to form the objects 50. In the embodiment shown in the figures theforming means comprises punch means 3.

The die means comprises a die 2 that is movable along a movementdirection B that is substantially orthogonal to the sheet material 40and to an advancement direction A thereof inside the forming apparatus.

The cavity means comprises at least one cavity 4 having a shape formedto correspond to that of the object 50 to be formed. The punch meanscomprises at least one shaped punch 3 having a shape that iscomplementary to that of the cavity 4 in such a manner as to shape theobject 50 by compression.

The apparatus 1 is further provided with crushing punch means 5comprising at least one crushing punch interacting and cooperating withthe die 2 for compressing a first portion 41 of the sheet material 40before the forming step in order to reduce and weaken the thicknessthereof, modify a structure of the material thereof, as explained ingreater detail further on in the description. For this purpose, the die2 comprises abutting means 6 that is suitable for supporting theaforesaid first portion 41 of sheet material and cooperating with thecrushing punch 5 to compress the latter. The abutting means 6 comprisesin the specific case a ridge provided inside the cavity 4.

The crushing punch 5 is maintained cooled, i.e. maintained at atemperature, in particular comprised between 15° C. and 40° C., such asto locally cool the first portion 41 and to obtain a structure of saidsheet material 40 substantially in amorphous phase at the first portion41. It is noted that the temperature of the crushing punch 5 isconsiderably lower than the temperature of the sheet material 40 that isheated to a temperature between 100° C. and 180° C., particularlybetween 140° C. and 165° C.

The crushing punch 5 may be cooled by correspondent cooling means, notshown in the figures, and comprising internal conduits for the passageof a cooling fluid or comprising materials with high thermalconductivity.

The crushing punch 5 comprises an end wall 5 a, e.g. of substantiallycircular shape, that presses the first portion 41 of sheet material 40against a corresponding abutting wall 6 a of the abutting means 6, e.g.a wall that also has a circular shape. The end wall 5 a is connected toa side wall 5 b, for example a cylindrical wall, by a connecting portion5 c of round shape.

The surface roughness of the end wall 5 a of the crushing punch 5 islower than 0.4 μm, in particular lower than 0.2 μm.

The die 2 is provided with conduits 8 for the passage of a coolingliquid suitable for cooling external surfaces of the cavity 4 and of theabutting means 6. In this manner, the material 40 adhering to theaforesaid external surfaces during forming can be quickly cooled toacquire the required mechanical features.

The cooled external surfaces of the abutting means 6 cooperate with thecrushing punch 5 to locally cool the first portion 41 and to make theamorphous phase structure of the sheet material.

The forming means 3 operates on a second portion 42 of the sheetmaterial 40 contiguous to the first portion 41. In particular, withreference to the embodiment shown in the figures, the second portion 42surrounds the first portion 41 and substantially forms the body of theobject 50.

The apparatus further comprises containing means 10 that includes acontaining element, a so-called bell, arranged for pressing the sheetmaterial 40 against a supporting wall 7 of the die 2 and retaining thesheet material 40 before forming. On the supporting wall 7 the cavity 4opens.

The containing element 10 defines a work volume 11 containing the punch3 and the crushing punch 5. The forming means further comprisesdelivering means 12 that delivers inside the work volume 11 apressurised fluid arranged to make sheet material 40 adherent to wallsof the cavity 4.

The crushing punch 5 is fixed to the containing element 10 in such amanner as to abut upon the first portion 41 of sheet material 40 andpress the first portion 41 against the abutting means 6 when the die 2is raised along the movement direction B and compresses the aforesaidsheet material 40 against a compression plate 13 of the containingelement 10.

In particular, the crushing punch 5 is fixed in an adjustable manner tothe containing element 10 so as to vary a thickness or amount ofcrushing d1 of the first portion 41 (FIG. 4). In other words, it ispossible to vary the position of the end wall 5 a of the crushing punch5 with respect to an abutting face 13 a of the compression plate 13,this determining a lower or greater crushing of the first portion 41against the abutting wall 6 a of the abutting means 6.

In one embodiment of the apparatus that is not illustrated in thefigures, the crushing punch 5 is mounted movably with respect to thecontaining element 10 and independently of the punch 3. In thisembodiment, the punch 3 and the crushing punch 5 are driven byrespective and independent actuating means, that is of known type and isnot illustrated in the figures.

The operation of the forming apparatus 1 and the corresponding formingmethod or process provide in a first step the advancement along theadvancement direction A of the sheet material 40, which has beenpreviously heated to a temperature that is sufficient to soften thesheet material 40, inside the forming apparatus 1. The latter isarranged in a first operating configuration W1 in which the die 2, thecontaining element 10 and the punches 3, 5 are spaced away from thesheet material 40 to enable sheet material to slide.

In a second step, the die 2 is moved along the movement direction B suchthat the sheet material 40 is compressed by the supporting wall 7against the compression plate 13 of the containing element 10 and thefirst portion 41 of sheet material 40 is compressed and crushed betweenthe abutting means 6 and the crushing punch 5, in a second operatingconfiguration W2 of the apparatus 1.

In this second operating configuration W2, the relative position betweenthe crushing punch 5 and the abutting means 6 and the force exerted bythe latter on the first portion 41 of sheet material 40 is such as toreduce the thickness thereof to a desired value d1.

The compression and crushing effect exerted by the crushing punch 5 andby the abutting means 6 not only leads to a reduction of the localthickness of the material, but also to a substantially radial or dialorientation of the fibres or chains of molecules that comprise thestructure of the plastics. This orientation is due to both the pressureexerted by the crushing punch 5 and to the circular shape of the endwall 5 a of the latter.

The proper orientation of the fibres of plastics is also promoted by thereduced surface roughness of the end wall 5 a of the crushing punch 5(roughness lower than 0.4 μm, in particular lower than 0.2 μm). Thissurface finishing also prevents, during compression and crushing,surface layers of the sheet material to be damaged or wrecked (forexample with micro-cracking or micro-incisions), this determining analteration of the mechanical characteristics of the material at thefirst portion 41.

Since the crushing punch 5 is maintained at a temperature comprisedbetween 15° C. and 40° C. and/or the abutting means 6 as well as thecavity 4 is cooled by the cooling liquid that flows in the conduits 8 ofthe die 2, the first portion 41 of sheet material whilst it iscompressed and crushed between the crushing punch 5 and the abuttingmeans 6 it is also cooled.

As known, the plastic polymer materials usually used in thermoforming(PP, PVC, PE, PET, PA, PS, PLA, starch-based biodegradable plastics,bio-based polymer materials such as, for example, PE and/or PP and/or PAobtained from renewable resources, biodegradable resources obtained froma microbial source such as, for example, PHA and the like) are formed oflong chains of molecules the orientation of which can be modified byplastic processing such as lamination, extrusion and the like. Thestructure of these materials can be further modified, after heating to atemperature in which the vitreous transition of the material occurs(so-called softening temperatures), from the cooling speed. In the caseof polypropylene (PP), for example, at high cooling speeds, at the endof the forming process the material has a structure that issubstantially in an amorphous step with limited portions in thecrystalline step. The amorphous phase gives the material plasticelasticity and resistance.

At low cooling speeds, at the end of the forming process the materialhas a structure that is mostly in crystalline phase and to a morelimited extent in an amorphous phase. The crystalline phase in this casegives lesser elasticity and greater fragility.

The aforesaid sheet plastics can be single-layered or multilayered,according to the specific applications.

Experimental tests conducted by the applicant have shown that the radialorientation obtained from the compression exerted by the crushing punchand the rapid cooling guaranteed by the crushing punch 5 and/or by theabutting means 6 enable a first portion 41 of sheet material 40 to beobtained that has a structure that is substantially weakened that can beeasily torn, perforated or pierced, for example by a tip of conicalshape. The rapid cooling, in particular, enables a structure of thematerial elastic and hardly fragile to be obtained, owing to which it ispossible to achieve perforation without the undesired detachment ofparticles, fragments, splinters of material.

FIG. 8 illustrates the effects of this perforation on an object 50obtained by thermoforming a sheet material of polypropylene having a 1.2mm thickness and in which a weakened portion 51 of the object 50 formedby the first portion 41 of sheet material 40 compressed by the crushingpunch 5, has been reduced in thickness to a value d1 equal to 0.3-0.75mm, in particular equal to 0.3-0.4 mm. As is noted, the fracture 52generated by a conical tip has a substantially radial pattern, i.e.according to the local orientation of the molecular chains of thestructure of the material.

The effect of the compression is clear, considering that the sheetmaterial that has the same thickness as that of the first portion 41(i.e. 0.3-0.75 mm) and is not subject to local compression by thecrushing punch 5 is very difficult to perforate and requires the use ofhigher compression forces.

It is appropriate to point out that owing to the shape of the crushingpunch 5—and in particular of the end wall 5 a and of the connectingportion 5 c of round shape—crushing the first portion 41 does not damageor tear an intermediate barrier layer that may be provided in the sheetmaterial 40 of multilayered type. The intermediate barrier layer is ofknown type, for example EVOH. In this manner, the integrity of thematerial and in particular of the barrier layer is guaranteed also atthe first portion 41.

In a third step of the forming process (forming step), in which theforming apparatus is in a third operating configuration W3, the punch 3of the forming means is moved along the movement direction B towards thedie 2 in such a manner as to progressively compress the sheet material40 inside the cavity 4 and form the object 50, whilst the crushing punch5 keeps compressed and crushed the first portion 41 against the abuttingmeans 5. In particular, the punch 3 operates on the second portion 42 ofthe material sheet 40 that is contiguous and surrounds the first portion41.

At the end of compression, or before the punch 3 is lowered completely,hot pressurised air can be delivered inside the work volume 11 tofacilitate adhesion of the sheet material 40 to the walls of the cavity4.

It should be observed that compressing and crushing the first portion 41of the material sheet 40 before the forming step (third step) of theobject 50 and maintaining this first portion 41 compressed and crushedduring this forming step, helps in obtaining the desired thickness d1requested in said first portion 41 with high precision and accuracy.

Experimental texts have shown that objects 50 having first portions 41substantially with the same thicknesses d1 can be made thanks to theapparatus and the method of the invention.

The histogram of FIG. 9 shows the results of a test performed on asample of 100 pieces on which the compression and the crushing of aportion to a nominal value of 0.35 mm has been made, the sheet materialhaving a starting thickness of 1.2 mm. It is observed that more than 70%of pieces have, at the crushed portion, a thickness comprised between0.34 mm and 0.37 mm and mostly all pieces have a thickness comprisedbetween 0.32 mm and 0.39 mm. The histogram shows the stability andrepeatability of the compression and crushing process of the portion ofsheet material.

Owing to the apparatus and to the forming method of the invention it isthus possible to make, by thermoforming of a sheet material, inparticular single or multilayered polymer plastics, objects having greatmechanical features of resistance and toughness that are at the sametime provided with one or more weakened, easily perforable, tearable,breakable portions. In other words, it is possible to make objects thatare traditionally obtainable only by injection moulding processes, thisenabling production costs to be reduced significantly.

A weakened portion is obtained by local compression, made by a suitablyshaped punch (crushing punch) and a simultaneous cooling process. Byvirtue of the pressure exerted by the punch and of the particularcircular shape and surface finishing of the end wall thereof, it ispossible, at the weakened portion, not only to reduce the thickness ofthe material but also to obtain a substantially radial or dialorientation of the fibres or chains of molecules that make up thestructure of the plastics. The reduced thickness and the radialorientation weaken the structure of the material, which can be moreeasily perforated or torn, for example by a tip.

Further, by rapidly cooling the weakened portion, in particular in thecase of polypropylene, a structure is obtained that is substantially inan amorphous phase with limited portions in a crystalline phase, i.e. astructure that gives the plastics elasticity and resistance. Owing tothis structure it is possible to make a perforation without having anundesired detachment of particles, fragments, splinters of material.

The forming apparatus and method of the invention further enable objectsprovided with weakened portions having precise and accurate thicknessvalues to be made. In particular, it is possible to obtain a desiredthickness requested in said weakened portions with high precision andaccuracy.

It should be eventually noted that the forming apparatus of theinvention is constructionally simple because it requires only thecrushing punch 5 to be inserted that can be fixed directly to thecontaining element 10.

FIG. 10 shows a variant of the forming apparatus of the invention thatdiffers from the embodiment above described and illustrated in FIGS.1-4, in that the forming means does not comprise punch means but itcomprises delivering means 12 that introduces a pressurized fluid (hotair) into the work volume 11, this fluid being arranged so as the sheetmaterial 40 adheres to the walls of the cavity 4 and thus forms theobject 50.

Also in this variant of the apparatus 1, during the third step (formingstep), in which the forming apparatus is in the third operatingconfiguration W3, while the pressurized fluid is being introduced intothe work volume 11, the crushing punch 5 keeps the first portion 41compressed and crushed against the abutting means 6.

FIGS. 5 to 7 illustrate schematically, and by way of non-limitingexample, an object 50 that is makable with the forming apparatus andmethod according to the invention that are disclosed above. The objectcomprises a cover or cap 50 that is usable for closing a container 60.The latter is, for example, a capsule for automatic beverage machinesthat is suitable for containing a percolable or soluble or infusionproduct.

The cover 50 comprises one annular cavity 55 that defines a, for exampleeccentric, protrusion 56 on the summit of which a weakened portion 51 isprovided that is formed by the first portion 41 of sheet material 40compressed by the crushing punch 5. This weakened portion 51 of thecover 50, by virtue of the local features of the plastics, can be easilyperforated by suitable dispensing means of an automatic beveragemachine.

The container 60 can also be made by the forming apparatus of theinvention provided in this case with a die and with punches that aresuitably shaped in such a manner as to make on a bottom wall 62 of saidcontainer a respective weakened portion 61 that can be easily perforatedby suitable extraction means of an automatic machine and/or bycooperation of the bottom wall 62 of said container 60 with suitablemeans for opening the capsule. Also in this case, the respectiveweakened portion 61 of the container 60 is made by compressing andcrushing a corresponding portion of sheet material by means of asuitable crushing punch.

It is obvious that the forming apparatus and method of the invention canbe used to form a thermoformable sheet material so as to make objects ofany shape and provided with one or more weakened portions that arearranged to be easily perforated, pricked or torn.

1-37. (canceled)
 38. A method for making objects by forming athermoformable sheet material, comprising the steps of forming saidobjects by interaction of a die assembly and a forming assembly, whereinsaid method further comprises before said forming step, compressing andcrushing a first portion of said sheet material by a crushing punchportion and maintaining said first portion crushed during said formingstep to reduce a thickness thereof and to orient chains of moleculesthat compose a structure of said sheet material at said first portion soas to weaken said structure and said first portion, whereby said firstportion is easily perforable, tearable and breakable.
 39. A methodaccording to claim 38, wherein said orienting step comprises radiallyorienting said chains of molecules that compose the structure of saidsheet material at said first portion.
 40. A method according to claim38, wherein said sheet material is selected from a single ormultilayered polymeric plastic material, comprising at least one of PP,PVC, PE, PET, PA, PS, PLA, biodegradable plastic starch based materials,bio-based polymeric materials including PE and/or PP and/or PA obtainedfrom renewable sources, and biodegradable plastic materials frommicrobial source such as for example PHA.
 41. A method according toclaim 38, and further comprising rapidly and locally cooling said firstportion of sheet material through said crushing punch portion duringsaid compressing and crushing step to obtain a structure in asubstantially amorphous phase.
 42. A method according to claim 38,wherein said forming step comprises forming a second portion of saidsheet material contiguous to said first portion.
 43. A method accordingto claim 38, and further comprising heating said sheet material at atemperature between 140° C. and 165° C. before said forming step.
 44. Amethod according to claim 38, wherein said crushing punch portion ismaintained at a temperature between 15° C. and 40° C. to locally coolsaid first portion and obtain a structure of said sheet material at saidfirst portion in a substantially amorphous phase.
 45. An object providedwith at least a weakened portion and made by a forming method as claimedin claim
 38. 46. Apparatus for performing the method according to claim38.
 47. Apparatus for making objects by forming a thermoformable sheetmaterial, comprising a) a die assembly provided with a cavity portion;b) a forming assembly cooperating with said cavity portion to form saidobjects in a forming step; c) a crushing punch portion cooperating withsaid die assembly for compressing and crushing a first portion of saidsheet material before said forming step and maintaining said firstportion crushed during said forming step to reduce a thickness thereofand orient chains of molecules that compose a structure of said sheetmaterial at said first portion; and d) a containing device for pressingsaid sheet material against a supporting wall of said die assembly thatdefines a work volume containing at least said crushing punch portion,said crushing punch portion being fixed to said containing device. 48.Apparatus according to claim 47, wherein said crushing punch portion isadjustably fixed to said containing device to vary a crushing thicknessof said first portion.
 49. Apparatus according to claim 47, wherein saidcrushing punch portion is maintained at a temperature between 15° C. and40° C. to locally cool said first portion and obtain a structure of saidsheet material at said first portion in a substantially amorphous phase.50. Apparatus according to claim 47, wherein said forming assemblyoperates on a second portion of said sheet material contiguous to saidfirst portion.
 51. Apparatus according to claim 47, wherein said formingassembly comprises a punch portion cooperating with said cavity portion.52. Apparatus according to claim 47, wherein said die assembly comprisesan abutting portion to support said first portion of said sheet materialand cooperate with said crushing punch portion to compress and crushsaid first portion of said sheet material.
 53. Apparatus according toclaim 47, wherein said die assembly contains conduits for passage of acooling liquid suitable for cooling external surfaces of said cavityportion and/or of an abutting portion of said die assembly. 54.Apparatus according to claim 47, wherein said forming assembly furthercomprises a delivering device to deliver a pressurized fluid into saidwork volume to make said sheet material adherent to walls of said cavityportion and form said objects.
 55. Apparatus according to claim 47,wherein said crushing punch portion comprises at least one crushingpunch provided with a substantially circular end wall for abutting andcompressing said first portion of said sheet material.
 56. Apparatusaccording to claim 55, wherein said end wall is connected to a side wallof said crushing punch by a round connecting portion.
 57. Apparatusaccording to claim 55, wherein said end wall has a surface roughnessless than 0.2 μm.
 58. Apparatus according to claim 47, wherein saidsheet material comprises one of a single or multilayered polymericplastic material comprising at least one of PP, PVC, PE, PET, PA, PS,PLA, biodegradable plastic starch based material, bio-based polymericmaterial, in particular PE and/or PP and/or PA obtained from renewablesources, and biodegradable plastic material obtained from microbialsource such as for example PHA.
 59. Apparatus for making objects byforming a thermoformable sheet material, comprising a die assemblyprovided with a cavity portion, and a forming assembly cooperating withsaid cavity portion to form said objects in a forming step, wherein saidapparatus further comprises a crushing punch portion cooperating withsaid die assembly for compressing and crushing a first portion of saidsheet material before said forming step and for maintaining said firstportion crushed during said forming step to reduce a thickness thereofand orient chains of molecules that compose a structure of said sheetmaterial at said first portion so that said structure and said firstportion are weakened portions, whereby said first portion is easilyperforable, tearable and breakable.
 60. Apparatus according to claim 59,wherein said crushing punch portion is maintained at a temperaturebetween 15° C. and 40° C. to locally cool said first portion and obtaina structure of said sheet material at said first portion in asubstantially amorphous phase.
 61. Apparatus according to claim 59,wherein said forming assembly operates on a second portion of said sheetmaterial contiguous to said first portion.
 62. Apparatus according toclaim 59, wherein said forming assembly further comprises a punchportion cooperating with said cavity portion.
 63. Apparatus according toclaim 59, wherein said die assembly further comprises an abuttingportion to support said first portion of said sheet material andcooperate with said crushing punch portion to compress and crush saidfirst portion of said sheet material.
 64. Apparatus according to claim59, wherein said die assembly contains conduits for the passage of acooling liquid suitable for cooling external surfaces of said cavityportion and/or of an abutting portion of said die assembly. 65.Apparatus according to claim 59, and further comprising a containingdevice arranged for pressing said sheet material against a supportingwall of said die assembly and that defines a work volume containing atleast said crushing punch portion.
 66. Apparatus according to claim 65,wherein said forming assembly further comprises a delivering device todeliver a pressurized fluid to said work volume to make said sheetmaterial adherent to walls of said cavity portion and form said objects.67. Apparatus according to claim 65, wherein said crushing punch portionis fixed to said containing device.
 68. Apparatus according to claim 67,wherein said crushing punch portion is adjustably fixed to saidcontaining device to vary a crushing thickness of said first portion.69. Apparatus according to claim 65, wherein said crushing punch portionis movable with respect to said containing device.
 70. Apparatusaccording to claim 59, wherein said crushing punch portion comprises aleast one crushing punch provided with a substantially circular end wallfor abutting on and compressing said first portion of said sheetmaterial.
 71. Apparatus according to claim 70, wherein said end wall isconnected to a side wall of said crushing punch by a connecting portionof round shape.
 72. Apparatus according to claim 70, wherein said endwall has a surface roughness lower than 0.2 μm.
 73. Apparatus accordingto claim 59, wherein said sheet material comprises one of a single ormultilayered polymeric plastic material comprising at least one of PP,PVC, PE, PET, PA, PS, PLA, biodegradable plastic starch based material,bio-based polymeric material, in particular PE and/or PP and/or PAobtained from renewable sources, and biodegradable plastic materialobtained from microbial source such as for example PHA.
 74. Athermoforming machine for making objects by forming a thermoformablesheet material comprising an apparatus according to claim
 47. 75. Athermoforming machine for making objects by forming a thermoformablesheet material comprising an apparatus according to claim 59.